(a) Field of Invention
The present disclosure of invention relates to flexible flat panel display devices such as those that use flexible plastic substrates and to manufacturing methods for the same.
(b) Description of Related Art
Older flat panel displays utilize rigid and brittle glass as the main support for thin film layers disposed thereon. Such an approach has the disadvantage that the display cannot be flexed even a little bit and that it cannot be safely dropped without fear of breakage. Also the conventional, thick glass substrates tended to be relatively heavy. In light of this, flexible flat panel displays using a flexible substrate such as one composed predominantly of a plastic have been developed so as to provide a flat panel display having light weight, impact resistance, and flexibility.
Flexible flat panel displays may include those of the liquid crystal display (LCD) type, the organic light emitting display (OLED) type, electrophoretic particle type, and so forth. The flexible flat panel displays include plastic support layers (substrates) for providing impact resistance and low production cost.
However, the plastic material in such substrates often has a relatively large coefficient of thermal expansion (COTE) and thus easily expands due to high temperature during the manufacturing process. In order to minimize this expansion problem, various thin films that are layered on the plastic substrates and used for displaying images are formed on the respective plastic substrates while limiting process temperature to no more than about 180° C. or lower. However, this constraint on process temperature process may prevent the manufacture of thin films having desired purities or other characteristics that are associated with good quality display devices.
Some of the information disclosed here in this Related Art section is written for providing clearer understanding of the nature of the invention and it may contain disclosure that does not form part of the prior art as known to persons of ordinary skill in the art.